Mrs Lim packs 35 big and small bags of candies for her pupils. Each big bag contains 12 candies and each small bag contains 7 candies. The bags contain 300 candies altogether. How many big bags of candies and how many small bags of candies does she pack?

Answer:there are 11 big-bags and 24 small-bags.Step-by-step explanation:there are x big-bags and y small-bags. so now we can know: (1) x + y = 35 (2) 12x + 7y = 300 in (1),we can do like this: both left and right x7 then (x + y)x7 = 35 x 7 then 7x + 7y = 35 x 7  then 7x + 7y = 245 now, (1)7x + 7y =245 (2)12x + 7y = 300 we can both left and right do this: (2) - (1) then (12x + 7y) - (7x + 7y) = 300 -245 then 12x + 7y - 7x - 7y = 300 -245 then 12x - 7x +7y - 7y =300 -245 then 5x =55 then 5x ÷ 5 = 55 ÷ 5 then x = 11 because x + y =35;x=11 so 11 + y =35 11+ y -11 = 35 -11 then y = 24 now we know:there are 11 big-bags and 24 small-bags.